Fixing The Light Engine On The WD 73732


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Liberator21
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Fixing The Light Engine On The WD 73732

Postby Liberator21 » Wed Mar 03, 2010 4:09 am

Hi, So I'm new to this forum (4th post?). I have a WD 73732 that I acquired when someone put it out to the trash. The set played beautifully for about 1 to 2 hours (In my 65 degree garage), then the colors would go off (purple faces), and I would get flickering / flashing in the picture. I read a lot of the info on this forum and others, and saw how many people were having this problem. Before I go further let me tell you a little about me. I've been into electronics since I was a kid, I went to college for electronics, I worked as a TV service tech for 20+ years, I service 2 way radios, audio gear, microwaves, whatever. I build radio equipment, amps transmitters, etc. I'm also a licensed ham, and I have an extensive test bench in my home. Not being one to back away from a challenge, and being I got the set for free, I gutted the set, and wired it up on the bench. I scoped out some key points on the light engine, and let her rip! After about 45 minutes, the color went out, and the picture started to flash. One of the waveforms I was monitoring at the color wheel went way out, and as the flashing got more violent, the waveform got more distorted. Honestly, I kind of expected this.
Figuring this was thermal, I went right to the sensor on the color wheel. There is an external sensor, it looks to be a hall effect sensor on a small circuit board next to the color wheel motor hub. I carefully sprayed the sensor with a small amount of freeze spray, and as expected, the picture jumped right back to normal as did the waveform. I then left the cover off the color wheel (it was hot in there when I removed it), and the set continued to function normally for the rest of the evening. I will perform this test one more time just to verify, then I will remove the color wheel, and attempt to ID the part, and a suitable replacement. Bear in mind we're talking about a few dollar part. If this truly fixes the problem, I'll be quite happy. I then might try to modify the color wheel cover to get some cooling air in there. It can't hurt. I hope this helps some of you out, but don't go ripping into your light engines quite yet! I only just diagnosed this, and I want to make sure it solves the problem. Meanwhile, check out the pictures. I shot some video, and I'm planning to post it on youtube (whe I get time). 8-)
Paul
Attachments
P1010555.JPG
Picture projected on shop ceiling. Note scope showing color wheel waveform in background.
P1010555.JPG (34.23 KiB) Viewed 25794 times
P1010554.JPG
Light engine with color wheel cover removed. Note scope probe.
P1010554.JPG (49.68 KiB) Viewed 25794 times
P1010565.JPG
Closeup of external sensor board on color wheel.
P1010565.JPG (34.39 KiB) Viewed 25794 times

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Re: Fixing The Light Engine On The WD 73732

Postby Eddie » Wed Mar 03, 2010 5:04 pm

So you're saying the color wheel sensor was over heating, causing the wheel to spin erratically?
--

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Wed Mar 03, 2010 5:17 pm

Yes the sensor was overheating. When I lifted the color wheel cover at the time of failure, I felt a considerable amount of heat. Similar to opening an oven door, just on a much smaller scale.
Was the bad signal causing the color wheel to spin erratically? Hard to say. There was no audible difference in the sound the motor made before or during the failure. I would think that pulse would be motor control, but it could also be a sync pulse for the video (maybe both). Hard to say without a schematic. The bottom line is, heat is the major factor here. I am working on some ideas for modifications to the color wheel housing to reduce the heat buildup. This should extend the life of the color wheel, the light tunnell, sensors etc. I can't be the first one to actually find the cause of this problem....Can I?

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Wed Mar 03, 2010 5:21 pm

By the way, here's a shot of the picture (on my ceiling), after hitting the sensor with freeze spray.
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P1010561.JPG
That picture is 9 feet wide!
P1010561.JPG (32.48 KiB) Viewed 25784 times

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Fri Mar 05, 2010 5:34 pm

Here's an update:
I was able to repeat the failure, and fix multiple times by heating and cooling the sensor.
I then removed the color wheel, and to my surprise found the sensor was not hall effect at all. It's an optical sensor. In the picture, you'll see the sensor board. The sensor has an IR emitter LED, and phototransistor in one package. They used devices like this for motor speed control on VCR head drums many years ago. As you can see from the picture, the board (and color wheel), and probably the whole light engine is made by Young Optics. They're on off-shore manufacturer of the wheels, and complete light engines. They have a website. I'm going to try and contact them. This part shouldn't be too difficult to source. I found a few with the same housing style in the Mouser catalog.
They run about 77 cents each. Notice the wires connected to the circuit board. The center one should be a bright yellow, not the almost brown it looks like now. Thats the excessive heating and cooling cycles. I'm going to try and come up with a way to cool the color wheel housing.

Paul
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ColorWheel Op Sensor.jpg
Color Wheel Optical Sensor Board.
ColorWheel Op Sensor.jpg (181.51 KiB) Viewed 25777 times

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Re: Fixing The Light Engine On The WD 73732

Postby deltatom » Tue Aug 24, 2010 2:42 am

Paul did you have any luck with the board. I have a wd-73732. I have replaced the LE twice and fixed the color plumung problem both times. Last time I got a hold of a good color wheel that was replaced under a mis diagnostic repair. After the color wheel replacement all was good for two months. The color wheel that I installed was documented at three weeks old when I got it. I don't think that there is any way the wheel failed that quickly. Also I have never had the noise that some have mentioned when the bearing starts to go. I believe you may have discovered an inherant problem with the heat issue on the sensor board. Have you had any luck finding a source for this board. If this solves my problem I will be one happy person. Mits is going to replace my set with a 73838. To top it off I can keep my 73732. This would make a great situation out of one that has been nothing but aggrivation. Please let me know what have as far as any updates with this issue.Thanks for the info that you have shared. Tom

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Re: Fixing The Light Engine On The WD 73732

Postby deltatom » Tue Aug 24, 2010 2:37 pm

I have been in touch with Young Optics. When I mentioned that the parts we need were for a WD-73732, I was informed that I needed to call MDEA as they had a contract them that they couldn't break. I then call my contact in Tiawan on his cell and am trying to find other sets that use some of these parts. We are going to try and find a set that we can order the part for that won't jeopardize their interests with MDEA.

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Wed Oct 27, 2010 4:07 pm

Forget about contacting Young Optics. I spoke with them as well. They were were very curious as to how I knew that part was the problem.
So much so that I got emails from corporate, and they called me! No real help though.Bottom line is, If you have the same problem as I had (Jittering Picture / Color shift), odds are it's the sensor on the color wheel.
The sensor is a Sharp GP2S40 Photointerrupter. It's a small inexpensive part, easily replaced. You just need to be real careful removing the color wheel so you don't break it. Then carefully remove the sensor board, and change the part. As far as I know, Sharp stopped making that part, so you'll have to find someone with old stock. I've tried a few other part numbers. None of them worked.
My other recommendation would be to add a cooling fan to blow on the area where the color wheel is housed, and if you're feeling spunky, make a metal (aluminum) cover with cooling fins to replace the phenolic cover on top. Just keep the cooling fins low. There's not much clearance once the engine is back in the cabinet. Don't put it back in the set without the top cover, you'll get dust problems.

Paul

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Fri Feb 18, 2011 7:58 pm

Any updates from anyone? My set continues to work fine.

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Re: Fixing The Light Engine On The WD 73732

Postby cbettano » Sun Mar 27, 2011 7:52 pm

Hi Liberator21. I am having the same problem with the same type of TV that i just picked up today for free from a friend. I would like to start with replacing the part mentioned
(Sharp GP2S40 Photointerrupter). Do you know where I can purchase this part?

Thanks

Carl

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Tue May 17, 2011 7:07 pm

Thank you Liberator 21 for giving me a clue to fixing the overheating problems with my TV. After 5 years of use I recently had to replace the lamp. Within a week the color wheel failed. Not knowing what the problem was I called in a service man. He told me that it was a color wheel failure and a replacement would cost $850.00 U.S. when a new Mitsubishi TV of similar design is currently selling for under $1,000.00. That's when I searched the internet for a replacement color wheel or other solution and came upon this Forum. However, after reading the blogs here, I too could not find a replacement Photointerrupter. But it occurred to me to try something else. Having learned that it was an overheating problem and knowing that the failure occurred immediately after I had installed the new lamp, possibly radiating increased amount of heat, I decided to try cooling the area as we do with computers. From our local electronics store, Fry's, I purchased a quiet, plastic, 4"x4" computer-case cooling fan of the highest volume they had for $20.00. I wanted a 120 volt fan but could only get a 12 volt one. When I discard a piece of electronic equipment I keep the power supply for "just in case". I happened to have one of proper voltage. I cut off the end connection and made the connection wire to wire. To the right of the lamp access panel there is a small vent area, which appears directly behind, or at least very close, to the color wheel. I attached the fan over the vent but that was not enough because of the blockage. So, I cut-out an opening to the size of the fan at the location of the vent. I cut it using a circular saw blade in a Dremel tool. I attached the fan to the plastic TV enclosure quite simply by using Gorilla brand duct tape. I plugged the power supply into the back of my amplifier so that the fan would go off when I turned the system off. The TV has performed flawlessly for three weeks now except for one evening when the room temperature was very warm. If it occurs again, I will purchase another fan and mount it next to this one to increase the volume of air.

I am very appreciative of Liberator 21 for sharing his discovery. I hope that my solution will help others as well.

Norm

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Wed May 18, 2011 3:27 am

Norm, I'm glad I could be of help. The place I bought the sensors from (Wrighthobbies.net), doesn't seem to carry them anymore. But they do carry a line following module kit that he clearly says has the sensors (I think it has two). So if you don't mind spending 15 bucks And doing a little desoldering, you'll be good to go. Ventilating that cabinet is paramount! You'll extend the life of that set by keeping it cool.
Paul

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Mon May 30, 2011 5:29 pm

Thank you again Liberator 21 for your advice.

Update:
As expected, see my previous post, the fan that I installed was not sufficient and the problem of green or black and white screen would return from time to time. To be clear, the fan that I originally installed was a Silenx, Ixtrema 80, 28cfm a little over 3" square. While shopping for an extra fan, I decided to purchase a larger one - a Silex, Ixtrema 120, 72cfm almost 6" square. It was under $20.00. The fan is so quiet that we cannot hear it and the TV now work flawlessly for many hours on end.

For anyone wishing to install a fan as I did, I highly recommend that you first cut out a smaller opening, the size of the grill, to the right of the lamp enclosure. From that smaller opening you will be able to determine exactly where you can enlarge the opening to the size of the larger fan while avoiding obstructions inside the cabinet.

Hopefully, from this inexpensive and simple solution we can get many more years out of our costly television sets.

Norm

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Tue Jun 07, 2011 5:12 pm

Question for Liberator 21
As my previous posts show, I have tried to correct the problem by cooling the area with a fan. Well, I'm sorry to report that they were a temporary solution. First I needed to upgrade to a larger fan which worked for a while and now the problem has recurred while using the larger fan. My question to you is: Has replacing the Photointerupter been a permanent solution for you or would you recommend that I try replacing the complete Color Wheel assembly? Thank you again for your advice.

Norm

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Sat Jun 11, 2011 10:53 pm

As I stated, the sensor fixed the issue For Me. It's always possible that the color wheel itself is bad, but I doubt it. I've been servicing TVs for a long time.
These optical sensors were notorious for failing in VCRs. Plus, its more likely that the sensor is going to have a thermal issue than the color wheel.
The sensor is cheap, a lot cheaper than the whole wheel. stop fooling around, and just replace it.

Paul

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Sun Jun 12, 2011 8:29 pm

Hi Paul. I found that Wright Hobbies now has the Sharp GP2S40 in stock for $1.99 each. Although I have never taken such a TV apart, after a while, I figured out how to slide out the assembly. I am now waiting for the replacement part. Thanks again for your help.

Norm

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Re: Fixing The Light Engine On The WD 73732

Postby Liberator21 » Tue Jun 14, 2011 4:18 pm

I'm glad you're doing it the right way, and I'm glad they have them back in stock. I might order a few extra just in case.
Once you figure out how to take the set apart, it's easy.
Just be very careful when removing the color wheel.
Also, if you can, add a fan blowing directly on the area that houses the color wheel.
The cooler you can keep things, the better.

Paul

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Wed Jun 15, 2011 12:49 am

I have not received the part yet. Any recommendation on how I should clean the color wheel? I know that it would need to be lint free. But, is there a product that I should use or products that I should definitely not use. I.E. could I use a wipe designed for glasses, or a wipe designed for a monitor screen for instance. Thanks again, your a great help. If you were nearby, I'd buy you a beer or glass of wine. Cheers!
Norm

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Re: Fixing The Light Engine On The WD 73732

Postby faleepay » Fri Jun 24, 2011 12:31 am

i got my wd73732 for free.. the guy i got it from told me it wouldnt power on so i knew right away it was the lamp,
so i replaced the lamp and bam it fired right up.
i knew it was to good to be true so later i find out after the first 15min of the tv being powered on with a great picture,
the colors start to flicker out to purple and blue
i can see green colors just fine but all the red turns to purple and yellow turns to blue...

so, would all i have to do is change the sensor on the color wheel and my color problem will be fixed?
or is there a diagnostics you would recommend to run?

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Fri Jul 01, 2011 3:02 pm

Liberator 21 was a great help. I finally did what he recommended and replaced the tiny, tiny little part at $1.99 would you believe. I was careful and did not need to clean the color wheel. You have to be careful as these parts are very tiny to work on. However, I found it to be easy to do. The good news is that it was exactly the problem. The TV has been working as new since then. Thanks to Liberator 21 for his time in posting here, he saved me at least $1,500 in the purchase of a similar new TV.

Good luck to whoever gets to read this.

Norm

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Re: Fixing The Light Engine On The WD 73732

Postby bigrob20 » Sun Jul 03, 2011 4:45 pm

I HAVE A WD-73732 I PURCHASED FROM CRAIGSLIST THE TV HAS A GREAT PICTURE WHEN WORKING RIGHT. HOWEVER I HAVE COLOR JUMPING AROUND PEOPLE TURN PURPLE THEN YOU CAN SEE A LINE GOING DOWN THE MIDDLE LIKE ITS ON DISPLAY. I HAD A REPAIR GUY COME OUT TO THE HOUSE AND HE SAID THAT ITS THE ENGINE OPTICAL LIGHT. PRIOR TO THE ONE GUY WHO COMES OUT TO THE HOUSE I SPOKE TO ANOTHER REPAIR GUY OVER THE PHONE AND HE SAID THE SAME THING. SO I WAS THINKING TOO PEOPLE SAME THING MUST BE RIGHT. I HAVE BEEM READING LOTS AND LOTS OF REVIEWS ON THIS TV AND EVERYONE SEEM TO HAVE THIS SAME PROBLEM. NOW THAT I AM READING THIS SIGHT I AM SHOCKED DOES ANYONE BELIEVE THAT THIS MIGHT FIX MY TV TO. ONLY THING IS I HAVE NEVER REPAIRED A TV BEFORE \ SO THE FIRST TIME WELL BE A CHALLENGE FOR ME.

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Thu Jul 14, 2011 4:05 pm

It appears to be the same problem I experienced and I fixed it as stated above. Good luck.

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Re: Fixing The Light Engine On The WD 73732

Postby NormL » Thu Jul 14, 2011 4:06 pm

It appears to be the same problem I experienced and I fixed it as stated above. Good luck.

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Re: Fixing The Light Engine On The WD 73732

Postby gump2388 » Mon Sep 26, 2011 1:26 am

Well i wanted to chime in and say that i bought a wd-73732 tv broken. Service guy said the optic engine was bad. So i bought it for cheap took a gamble after seeing this post and it fixed my tv!! Thanks alot guys for passing this along!! I bought me some spare sensors cause im sure it will do it again!! Thanks

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Re: Fixing The Light Engine On The WD 73732

Postby risaac928 » Sun Oct 16, 2011 9:11 pm

Well...I am going to attempt this myself. Has anybody posted any pics or DIY videos on YouTube.

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Re: Fixing The Light Engine On The WD 73732

Postby risaac928 » Mon Oct 17, 2011 2:06 am

Going to attemp this repair on my TV... Are there any DIY videos or pictures....

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Re: Fixing The Light Engine On The WD 73732

Postby risaac928 » Fri Oct 28, 2011 3:29 am

Well I replaced the sensor but now my lamp indicator is blinking Orange....

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Re: Fixing The Light Engine On The WD 73732

Postby razyfoo » Sun Nov 20, 2011 3:56 am

Hey guys. New to this so Im sorry if I ask a dumb question. I have recently acquired a 73732 and it blinks the error code 61 which I found out is for the light engine. It does not power the screen on at all, so I am wondering if anyone on here would know if these fixes may work for my tv as well, or if I actually will need to replace the entire light engine. Thanks

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Re: Fixing The Light Engine On The WD 73732

Postby alb88 » Tue Dec 20, 2011 7:21 pm

Hello,

Can someone please post a picture on how you guys install a fan inside the TV. I too having problem with WD73732. Thank you

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Re: Fixing The Light Engine On The WD 73732

Postby gump2388 » Sat Jun 02, 2012 12:45 am

i didnt change anything as far as cooling goes. i figured if i had to spend 2.99 every 2 or so years i could afford that. plus it gives me the chance to clean the dust out of the back too

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Re: Fixing The Light Engine On The WD 73732

Postby gump2388 » Sat Jun 02, 2012 12:54 am

this should be a stickie this actually works on serveral different models includeing the 65 and 73 inches

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Re: Fixing The Light Engine On The WD 73732

Postby sviscus » Sat Aug 06, 2016 7:38 pm

Has anyone found a replacement for the Sharp GP2S40 part?



Steve


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